Add 1 teaspoon oil to pan; swirl to coat. Add julienned yellow squash and a pinch of salt to pan; sauté 2 to 3 minutes. Remove squash from pan, keep warm. Add 1 teaspoon oil to pan; swirl to coat. Add julienned zucchini and a pinch of salt to pan; sauté 2 to 3 minutes. Remove zucchini from pan, keep warm. Add 1 teaspoon oil to pan; swirl to coat. Add carrots and a pinch of salt to pan; sauté 2 to 3 minutes. Remove carrot from pan, keep warm. Add 1 teaspoon oil; swirl to coat. Add mushrooms and a pinch of salt to pan; sauté 4 to 5 minutes. Remove from pan, keep warm.